1. Field of the Invention
The present invention relates to image down-sampling coding method and device, and more particularly, to method and device for performing an image down-sampling process from MPEG-4 to H.264 at a high speed.
2. Description of the Related Art
Thanks to development of computers and networks, a variety of data can be transmitted from a transmission party to a reception party. There have been developed multimedia standard compression formats for transmitting large-capacity multimedia data through networks. There have been introduced various video transcoding methods of performing conversion processes suitable for circumferences of the transmission party and the reception party by considering QoS (Quality of Service) of both parties Such video coding methods are roughly divided into a transcoding method in a pixel domain and a transcoding method in a DCT (Discrete Cosine Transform) domain.
The best transcoding method in view of image quality is a cascaded pixel-domain transcoding method of decoding input bit streams of images and encoding the decoded images again. However, since the encoding process is performed once more, such a conventional method has a problem with increase in complexity. Therefore, in order to decrease the complexity of calculation, efficient transcoding methods for down-sampling an image in the DCT domain have been studied and developed.
FIG. 1 shows a configuration of an H.264 encoder according to a related art.
The conventional H.264 encoder includes a loop filter 110. When the transcoding process of down-sampling an image from MPEG-4 to H.264 is performed, there is a problem that a direct transcoding in the DCT domain is impossible due to the H.264 non-linear loop filter 110.
Therefore, an efficient transcoding method which can reduce the complexity while maintaining the image quality is required.